Recall that all sentences have a subject and a verb: who or what the sentence is about, and what action is being performed. Some sentences also include an object, or the item being acted upon by the subject.
What you may not yet know, however, is that there are two types of objects: direct and indirect. A direct object is an object that directly receives the action of the verb, while an indirect object is impacted by the verb's action but is not the direct recipient.
EXAMPLEIn the sentence "I brewed my sister a cup of tea," the cup of tea is the direct object because it is what's being brewed, and "my sister" is the indirect object because - while she is affected by the brewing of the tea - she herself is not being brewed. To help make the relationship between these parts of the sentence clearer, the sentence could be rephrased to say, "I brewed a cup of tea for my sister."
Therefore, the three most common sentence patterns you are likely to encounter are:
1a. Subject + Verb
The simplest of sentence patterns is composed of a subject and verb, without a direct object or subject complement. It uses an intransitive verb, which is a verb that does not require a direct object.
EXAMPLEIn the sentence "Control rods remain inside the fuel assembly of the reactor," "rods" is the subject and "remain" is the verb.
EXAMPLEIn the sentence "The development of wind power practically ceased until the early 1970s," "development" is the subject and "ceased" is the verb.
1b. Subject + Verb + Direct Object
Another common sentence pattern uses the direct object, along with the subject and the verb.
EXAMPLEIn the sentence "Silicon conducts electricity in an unusual way," the subject is "silicon," the verb is "conducts," and the direct object is "electricity."
EXAMPLEIn the sentence "The anti-reflective coating on the silicon cell reduces reflection from 32 to 22 percent," the subject is "coating," the verb is "reduces," and the direct object is "reflection."
1c. Subject + Verb + Indirect Object + Direct Object
Finally, the sentence pattern with the indirect object and direct object is similar to the previous pattern.
EXAMPLEIn the sentence "I am writing her about a number of problems that I have had with my computer," the subject is "I," the verb is "am writing," the indirect object is "her," and the direct object is "problems."
EXAMPLEIn the sentence "Austin, Texas has recently built its citizens a system of bike lanes," the subject is "Austin, Texas," the verb is "built," the indirect object is "citizens," and the direct object is "system."
Also remember that sentences contain clauses, or groups of words that contain a subject and a verb. Clauses may be independent or dependent.
An independent clause can form a sentence on its own.
EXAMPLEThe dog ran.
A dependent clause cannot form a sentence of its own.
EXAMPLEfor miles and miles
The way in which clauses are combined determines the sentence type and punctuation needs.
There are three main types of sentences:
3a. Simple Sentences
A simple sentence is one that contains a subject and a verb but no other independent or dependent clause.
EXAMPLEOne of the tubes is attached to the steel instrument.
EXAMPLEThere are basically two types of stethoscopes.
In the above sentence, the subject and verb are inverted, meaning that the verb comes before the subject. However, it is still considered a simple sentence.
EXAMPLETo measure blood pressure, a sphygmomanometer and a stethoscope are needed.
This sentence has a compound subject - that is, there are two subjects - but it is also considered a simple sentence.
Command sentences are a subtype of simple sentences. These sentences are unique because they don’t actually have a subject.
EXAMPLEMake sure to take good notes today.
EXAMPLEAfter completing the reading, answer the following questions.
In each of these sentences, there is an implied subject: you. These sentences are instructing the reader to complete a task. Command sentences are the only sentences in English that are complete without a subject.
3b. Compound Sentences
A compound sentence is made up of two or more independent clauses joined by a coordinating conjunction (e.g., for, and, nor, but, or, yet, so) and a comma, an adverbial conjunction and a semicolon, or just a semicolon.
EXAMPLEI have an active sweet tooth, so I have to be careful when eating dessert!
EXAMPLESome cuffs hook together; others wrap or snap into place.
3c. Complex Sentences
A complex sentence is made up of one independent clause and one or more dependent clauses.
When the independent clause comes first, no comma is needed in between the clauses.
EXAMPLEThe dog ran for miles and miles.
EXAMPLEHe felt hungry until the next morning.
When the dependent clause comes first, a comma is needed in between the clauses.
EXAMPLEUntil the last runner came through, he could not leave his post.
EXAMPLEBecause she felt thirsty, she drank the entire water bottle.
Source: This content has been adapted from Lumen Learning's "Common Sentence Structures" tutorial.